In a small saucepan, combine the sugar with 1 cup of the cold water.
Heat over medium heat, stirring occasionally, until the sugar is completely dissolved. Remove from the heat and let the simple syrup cool.
In a large pitcher, combine the lemon juice, cooled simple syrup, and remaining cold water. Stir well.
Add the blue food coloring and stir until evenly combined.
Add ice to the pitcher or refrigerate until ready to serve.
Pour into glasses filled with ice and garnish with lemon slices and fresh mint, if desired.
Notes
- Make sure the sugar is totally dissolved when you're making the simple syrup so your lemonade doesn't end up gritty.- Let the syrup cool completely before mixing it with the lemon juice to avoid watering down the lemonade.